Fluid actuated gyroscopes have many practical applications but are particularly suitable for use in guidance systems of the single operational, or expendible, variety. Such gyroscopes should be of simple construction, inexpensive, and highly reliable. Rotation of the rotor must be initiated with-in a very short period of time (typically a fraction of a second) after the receipt of the signal, must come up to a high speed within a similar short period of time thereafter, and should sustain a useful speed for a relatively long period of time (typically 15 to 60 seconds). Both volume and weight should be kept as low as possible.
Many kinds of fluid actuated gyroscopes have been known and used in the past. One general kind is typified by the gyroscope described in the Hayner et al. U.S. Pat. No. 3,287,982. This patent describes a gyroscope having a fluid tight housing within which a hollow rotor is mounted for rotation. The rotor is formed with two or more orifices providing communication between the interior and exterior thereof. In operation, the entire case including the interior of the rotor is charged with gas under pressure. In order to actuate the gyroscope a means is provided for venting the case to the atmosphere whereupon the gas between the exterior of the rotor and the interior of the case escapes rapidly. The gas within the hollow rotor can escape only through the orifices which are located and shaped so that the reaction forces caused by the flow of fluid causes the rotor to be accelerated rapidly. One of the disadvantages of a gyroscope of this kind is that only that energy which is stored within the relatively small volume of the interior of the rotor is actually utilized in producing rotation.
Another kind of gyroscope which has been used in the past is typified by the unit described in the Boothroyd et al. U.S. Pat. No. 3,102,430. This patent describes a gyroscope having a gas tight housing, an outer gimbal within the housing, an inner gimbal within the outer gimbal, and a rotor mounted for rotation within the inner gimbal. The inner gimbal is hollow and of generally spherical shape. The rotor is provided with a number of impeller blades, or vanes, around its periphery. The inner gimbal is provided with a number of orifices adjacent to the rotor blades which orifices provide communication between the interior and the exterior of the inner gimbal. The entire case is charged with gas under pressure. In order to accelerate the rotor, the interior of the inner gimbal is vented to the atmosphere whereupon the remainder of the gas flows through the orifices in the inner gimbal and strikes the impeller blades of the rotor, accelerating it rapidly. This kind of gyroscope has a number of disadvantages. For example, after the rotor is brought up to speed, the impeller blades create a considerable amount of wind resistance thereby tending to decelerate the rotor. Additionally, this gyroscope has a complicated venting and caging mechanism.
It is a general object of the present invention to provide a simplified and improved fluid actuated gyroscope.